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A023814
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Number of associative binary operations on an n-set; number of labeled semigroups.
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12
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OFFSET
| 0,3
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LINKS
| Eric Postpischil Posting to sci.math newsgroup, May 21 1990
C. Noebauer, Home page [broken link]
C. Noebauer, The Numbers of Small Rings
C. Noebauer, Thesis on the enumeration of near-rings
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
Index entries for sequences related to semigroups
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CROSSREFS
| Cf. A001423, A001426, A023813, A023815, A027851.
a(n)+A079172(n)=A002489(n)
Sequence in context: A072402 A092084 A099715 * A062126 A113670 A156468
Adjacent sequences: A023811 A023812 A023813 * A023815 A023816 A023817
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KEYWORD
| nonn
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AUTHOR
| Lyle Ramshaw (ramshaw(AT)pa.dec.com)
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